Directions

1Heat oven to 350°F (325°F for dark or nonstick pan). Make cake as directed on box for 13x9-inch pan. Cool 10 minutes. Run knife around sides of pan to loosen cake; remove from pan to cooling rack. Cool completely, about 1 hour. For easier handling, refrigerate or freeze cake 30 to 60 minutes or until firm.

2Use serrated knife to cut cake as shown in diagram (for piano bench, cut 4 1/2x1 1/2-inch piece; cut horizontally in half to make bench lower than piano, if desired). Place cake on tray. Place about 2 tablespoons frosting in small resealable food-storage plastic bag. Frost cake with thin layer of frosting to set crumbs. Refrigerate or freeze 30 to 60 minutes to set frosting. Frost entire cake.